sysdeps/posix/signal.c

   1 /* Copyright (C) 1991, 1992, 1996 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <signal.h>
  21
  22
  23 /* Set the handler for the signal SIG to HANDLER,
  24    returning the old handler, or SIG_ERR on error.  */
  25 __sighandler_t
  26 signal (sig, handler)
  27      int sig;
  28      __sighandler_t handler;
  29 {
  30   struct sigaction act, oact;
  31
  32   /* Check signal extents to protect __sigismember.  */
  33   if (handler == SIG_ERR || sig < 1 || sig >= NSIG)
  34     {
  35       __set_errno (EINVAL);
  36       return SIG_ERR;
  37     }
  38
  39   act.sa_handler = handler;
  40   if (__sigemptyset (&act.sa_mask) < 0)
  41     return SIG_ERR;
  42   act.sa_flags = SA_ONESHOT | SA_NOMASK | SA_INTERRUPT;
  43   act.sa_flags &= ~SA_RESTART;
  44   if (__sigaction (sig, &act, &oact) < 0)
  45     return SIG_ERR;
  46
  47   return oact.sa_handler;
  48 }
  49
  50 weak_alias (signal, ssignal)